Czech Sourdough Mushroom Soup
Czech sourdough mushroom soup turns sourdough starter, dried mushrooms, potatoes, and eggs into a creamy, tangy bowl that tastes rustic, filling, and deeply savory.
This old style soup is a smart way to use sourdough discard or active starter. The starter thickens the broth and adds a gentle tang, while dried mushrooms give the soup a rich forest flavor. Potatoes make it hearty, eggs add protein, and a little butter and cream bring everything together.
Why You Will Love This Recipe
- Deep mushroom flavor: Dried mushrooms create a dark, savory broth that tastes like it simmered all day.
- Creamy without flour: Sourdough starter thickens the soup and adds a pleasant tang.
- Simple pantry meal: Potatoes, onion, eggs, and starter turn into a full meal for four.
- Flexible eggs: Scramble them into soft ribbons or poach them right in the soup.
Fabian’s Budget & Health Tip: Use sourdough discard straight from the fridge if it smells pleasantly tangy, not sharp or spoiled. For the mushrooms, a small amount of dried mushrooms gives more flavor than a larger amount of fresh mushrooms, so it is often the better value. This soup also gives you fiber from potatoes, protein from eggs, and minerals from mushrooms.
Ingredients (Serves 4)
- 1 oz dried mushrooms (28 g)
- 4 cups hot water for soaking mushrooms (950 ml)
- 2 tablespoons butter (28 g), divided
- 1 medium yellow onion, finely chopped, about 1 cup (150 g)
- 1 1/2 lb potatoes, peeled and diced (680 g)
- 1 teaspoon caraway seeds (2 g)
- 1 teaspoon fine salt (6 g), plus more to taste
- 1/2 teaspoon black pepper (1 g), plus more to taste
- 3 cups water or light vegetable broth (710 ml)
- 1 cup sourdough starter or sourdough discard, 100 percent hydration (240 g)
- 4 large eggs
- 1/2 cup heavy cream or sour cream (120 ml)
- 2 tablespoons chopped fresh chives (6 g)
Step-by-Step Instructions
1. Soak and Cook the Mushrooms
Place the dried mushrooms in a bowl and cover them with the hot water. Let them soak for 20 to 30 minutes, until they look plump and the water turns deep brown. Pour the soaking liquid through a fine sieve into a clean bowl and save it. Rinse the mushrooms if they feel gritty, then chop them into bite size pieces.
Add the chopped mushrooms and the reserved mushroom liquid to a small pot. Simmer for 10 minutes. The liquid should smell earthy and rich, like a pot of forest broth.
2. Start the Potato Base
Melt 1 tablespoon butter in a large soup pot over medium heat. Add the onion and cook for 4 to 5 minutes, stirring often, until it softens and smells sweet. Do not brown it too much. Add the potatoes, caraway seeds, salt, black pepper, and 3 cups water or light broth.
Bring the pot to a gentle boil, then lower the heat. Simmer for 12 to 15 minutes, until the potatoes are tender when pierced with a fork and the caraway smells warm and toasty.
3. Add the Mushrooms and Sourdough Starter
Pour the cooked mushrooms and their liquid into the potato pot. In a separate bowl, whisk the sourdough starter with 1 cup of hot soup broth until smooth. This helps prevent lumps. Slowly stir this mixture back into the soup.
Keep the heat gentle. Cook for 6 to 8 minutes, stirring often, until the soup looks slightly thicker and creamy. Avoid a hard boil, because strong heat can make the starter taste harsh and may cause the soup to separate.
4. Add the Eggs
For scrambled style eggs, beat the eggs in a bowl. Slowly pour them into the gently simmering soup while stirring in wide circles. The eggs will set into soft ribbons. Stop stirring once you see pale yellow strands floating through the broth.
For poached eggs, crack each egg into a small cup. Make four gentle spaces in the soup and slide in the eggs. Cover the pot and cook for 3 to 5 minutes, until the whites turn opaque and the yolks are as soft or firm as you like.
5. Finish with Butter, Cream, and Chives
Turn off the heat. Stir in the remaining 1 tablespoon butter and the cream or sour cream. Taste the soup and add more salt or black pepper if needed. The soup should taste tangy, earthy, creamy, and lightly peppery.
Ladle into bowls and finish with chopped chives. Serve hot, while the potatoes are soft and the broth is silky.
Expert Troubleshooting & FAQs
Why did my soup get lumpy?
The sourdough starter may have hit the hot broth too fast. Whisk the starter with a cup of hot soup liquid first, then add it slowly to the pot. Stir often while the soup thickens.
Can I use sourdough discard instead of active starter?
Yes. Sourdough discard works well here because the recipe uses it for tang and body, not rising. Use discard that smells pleasantly sour, like yogurt or bread dough. Do not use starter that smells rotten, moldy, or strongly like nail polish remover.
Can I make this soup without cream?
Yes. You can skip the cream and add an extra tablespoon of butter for richness. For a lighter finish, stir in a spoonful of plain yogurt off the heat, but do not boil it.
What mushrooms work best?
Dried porcini, mixed wild mushrooms, or dried cremini all work. Porcini gives the strongest flavor. If your mushrooms have grit, rinse them after soaking and strain the soaking liquid carefully.
How do I store leftovers?
Cool the soup and store it in a covered container in the fridge for up to 3 days. Reheat it gently over low heat, stirring often. Do not boil it hard, especially if you used sour cream.
Estimated Nutritional Facts
These values are rough estimates per serving and can change based on the exact starter, cream, and mushrooms you use.
- Calories: 360
- Protein: 14 g
- Carbs: 42 g
- Fats: 16 g
Czech Sourdough Mushroom Soup
Ingredients
- 1 oz dried mushrooms (28 g)
- 4 cups hot water for soaking mushrooms (950 ml)
- 2 tablespoons butter (28 g), divided
- 1 medium yellow onion, finely chopped, about 1 cup (150 g)
- 1 1/2 lb potatoes, peeled and diced (680 g)
- 1 teaspoon caraway seeds (2 g)
- 1 teaspoon fine salt (6 g), plus more to taste
- 1/2 teaspoon black pepper (1 g), plus more to taste
- 3 cups water or light vegetable broth (710 ml)
- 1 cup sourdough starter or sourdough discard, 100 percent hydration (240 g)
- 4 large eggs
- 1/2 cup heavy cream or sour cream (120 ml)
- 2 tablespoons chopped fresh chives (6 g)
Instructions
- 1. Soak and Cook the Mushrooms. Place the dried mushrooms in a bowl and cover them with the hot water. Let them soak for 20 to 30 minutes, until they look plump and the water turns deep brown. Pour the soaking liquid through a fine sieve into a clean bowl and save it. Rinse the mushrooms if they feel gritty, then chop them into bite size pieces. Add the chopped mushrooms and the reserved mushroom liquid to a small pot. Simmer for 10 minutes. The liquid should smell earthy and rich, like a pot of forest broth.
- 2. Start the Potato Base. Melt 1 tablespoon butter in a large soup pot over medium heat. Add the onion and cook for 4 to 5 minutes, stirring often, until it softens and smells sweet. Do not brown it too much. Add the potatoes, caraway seeds, salt, black pepper, and 3 cups water or light broth. Bring the pot to a gentle boil, then lower the heat. Simmer for 12 to 15 minutes, until the potatoes are tender when pierced with a fork and the caraway smells warm and toasty.
- 3. Add the Mushrooms and Sourdough Starter. Pour the cooked mushrooms and their liquid into the potato pot. In a separate bowl, whisk the sourdough starter with 1 cup of hot soup broth until smooth. This helps prevent lumps. Slowly stir this mixture back into the soup. Keep the heat gentle. Cook for 6 to 8 minutes, stirring often, until the soup looks slightly thicker and creamy. Avoid a hard boil, because strong heat can make the starter taste harsh and may cause the soup to separate.
- 4. Add the Eggs. For scrambled style eggs, beat the eggs in a bowl. Slowly pour them into the gently simmering soup while stirring in wide circles. The eggs will set into soft ribbons. Stop stirring once you see pale yellow strands floating through the broth. For poached eggs, crack each egg into a small cup. Make four gentle spaces in the soup and slide in the eggs. Cover the pot and cook for 3 to 5 minutes, until the whites turn opaque and the yolks are as soft or firm as you like.
- 5. Finish with Butter, Cream, and Chives. Turn off the heat. Stir in the remaining 1 tablespoon butter and the cream or sour cream. Taste the soup and add more salt or black pepper if needed. The soup should taste tangy, earthy, creamy, and lightly peppery. Ladle into bowls and finish with chopped chives. Serve hot, while the potatoes are soft and the broth is silky.
